I have spent 36 years around light aircraft as PPL, Instructor, examiner, NPPL,
and engineer. I have always pulled through the 4 cylinder horizontal opposed engines on first flight of the day. I wait for a quiet moment and listen for any odd noise and check compressions. On one occasion heard a hissing sound from under the cowling. It proved to be a cylinder head cracked two thirds of the way round and would have come off on the next flight. SO 36 years of checking has saved one forced landing!!